Cryptex

The word cryptex is a neologism coined by the author Dan Brown for his 2003 novel The Da Vinci Code, denoting a portable vault used to hide secret messages.

[1] The (first) cryptex featured in the novel The Da Vinci Code is described as a stone cylinder comprising "five doughnut-sized disks of marble [that] had been stacked and affixed to one another within a delicate brass framework"; end caps make it impossible to see inside the hollow cylinder.

Each of the disks is carved with the entire alphabet and can be rotated independently of the others to create different letter-alignment combinations, including but not limited to words, initialisms, and anagrams.

Although it is not clear whether the alphabet in question preserves the U/V and/or I/J distinctions and/or includes the letter W, when only the alignment of the disks with respect to each other is considered, the number of potential combinations is between 234 (279,841) and 264 (456,976); if the mechanism treats combinations having the same disk alignment but different degrees of rotation around the cylinder's long axis as distinct, as does a multiple-wheel combination lock or slot machine employing an indicator bar along which the specified numbers are to be aligned, this number rises to between 235 (6,436,343) and 265 (11,881,376).

The cryptex works "much like a bicycle's combination lock", and if one arranges the disks to spell out the correct password, "the tumblers inside align, and the entire cylinder slides apart" (p. 200).